'same-toothed' originates from Modern English, specifically formed by joining the adjective 'same' and the past-participial adjective 'toothed' (from 'tooth'), where 'same' meant 'identical' and 'tooth' meant 'tooth'.

'same-toothed' was formed in Modern English as a compound of 'same' + 'toothed' (from Old English 'tōþ' / 'tooth'); it is a transparent compounding rather than a word with a long separate historical development.

Initially, it has meant 'having teeth that are the same' and that basic meaning has remained stable into current usage.